how long does mating/fertilization carryover? 2 examples

1. I bought a hen that was with a rooster until I brought her home. She did not lay for a week (stress of transition). Will her first several eggs be fertile or not???

2. I have several different types of chickens that free range together. If and when I do decide to breed any I want them to breed true - so will have to put them in a breeding pen. How long will I have to wait after isolating appropriate rooster/hen combo - to know that the eggs are fertilized by the rooster I want them to be fertilized by???